Method of recording on a dual layer record carrier, and device for recording on a dual layer record carrier

ABSTRACT

The invention relates to a method of recording information on a recordable multi-layer record carrier, such as a dual layer DVD disc. The invention further relates to a recording device in which the above method is implemented.

The invention relates to a method of recording information on arecordable multi-layer record carrier, such as a dual layer DVD disc.The invention further relates to a recording device in which the abovemethod is implemented.

DVD-ROM discs are well known. This read-only type of record carriers isused for storing large amounts of information, such as for exampledigitally encoded movies. To be able to store even larger amounts ofinformation, a record carrier may comprise multiple information layers,that is, layers in which the information is stored in the form ofoptically detectible areas. Dual layer DVD-ROM discs, comprising twosuch information layers, are currently well known.

Recordable DVD discs, both the write-once type (such as DVD+R) and therewritable type (such as DVD+R(W), are used for recording large amountsof information. Recently, dual layer versions of these recordable DVDdiscs have been introduced. Such a dual layer disc comprises twoinformation layers, generally referred to as the L0 and L1 layers. TheL0 layer is the information layer located closest to the side of a discwhere a radiation beam, such as a laser beam, used for reading and/orrecording the information enters the disc.

The information is stored on these record carriers according to specificrules and layouts, generally referred to as Formats, which are describedin documents referred to as a Standards.

It is a problem that the information recorded on a dual layer recordableDVD disc cannot always be reproduced on a DVD-ROM player without errors.This, so-called compatibility issue, is especially a problem since alarge installed base of DVD-ROM players is already available all aroundthe world.

It is an object of the present invention to provide a method ofrecording a dual layer recordable DVD disc in such a way that it can bereproduced in DVD-ROM players without errors. The DVD-ROM player may bea player installed, for example in a Personal Computer (PC), or may be astand-alone DVD-ROM player.

This object is achieved by the method according to the present inventionwherein information is incrementally recorded on the disc such that theamount of information written on layer L0 is substantially equal to thatwritten on layer L1.

It was observed that the compatibility problem arises in two cases: 1)when the data is placed entirely on only one information layer, or 2)when the data is placed on both layers, with layer L0 totally filled andlayer L1 only partially filled. It appeared that these two cases arenon-compliant with the present DVD-ROM Standard because: 1) The DVD-ROMstandard states that the information area on the information layer L0must be about the same size as the information area on the informationlayer L1, and/or 2) when a drive accesses the beginning of informationlayer L1 (located at the outside of the disc) it will first jump fromlayer L0 to layer L1 and then move its tray. However, if the area onlayer L1 to which it jumps is unwritten, a drive will most likely crash.

According to an aspect of the present invention this compatibilityproblem is solved by modifying the Format of the recordable DVD discs insuch a way that a method of recording information has the possibility toincrementally fill the disc with information such that the amount ofinformation written on layer L0 is substantially equal to that writtenon layer L1.

The current Format does not support such an incremental filling processbecause once information is written to layer L1 and the written area onlayer L1 become just as large as the written area on layer L0, then thedisc is considered full and no information can be added anymore. This isbecause the Logical Address is zero at the beginning of the User DataArea on layer L0 (see FIG. 1) and increase linearly to the end of layerL0 up to the Middle zone. Then, after a layer jump, it increaseslinearly on layer L1 starting at the Middle zone towards the lead-outzone (indicated as SClosure in FIG. 1 in which the two informationlayers L0 and L1 are schematically shown). Hence, all of the blocks inthe Middle zone, both on layer L0 and on layer L1, are lost (that is,are unavailable for recording information). Preferably, these blocksshould be available for recording information.

The basic obstruction in the Format is that it is only allowed to recordinformation sequentially in Fragments and in Sessions (a Sessionsconsisting of one or more Fragments). This implies that one couldtemporarily skip over a large area on layer L0 by declaring it aFragment. However, such a skipped Fragment must be written in itsentirety before the disc is closed. This is because all Fragments in aSession must be closed before closing a Session, and because onlyrecordable discs with all closed Sessions (that is, a closed disc) areDVD-ROM compliant.

According to an aspect of the present invention a Fragment is allowed toremain open after closing a Session. By allowing the Fragment to remainopen after closing the Session, it is made a special type of Fragment.Therefore it is referred to as a Hierarchical Fragment. It is calledhierarchical because it may be contained within a Fragment and it maycontain itself other Fragments. Preferably, it is a Fragment whichitself contains all of the information required to register (that is,create) all Fragments and hierarchical Fragments it may contain.

According to an embodiment of the invention, a Session has a layout asshown in FIG. 2A and a Fragment has a layout as shown in FIG. 2B. Eachsession starts with a session lead-in area (SIntro) and end with asession lead-out area (SClosure).

Now, a Hierarchical Fragment has the layout as shown in FIG. 2C. Itstarts with a lead-in area (FIntro) and end with a lead-out area(FClosure). A Hierarchical Fragment may contain further HierarchicalFragments. This may be physically distributed over the two layers of adual layer disc as is shown in FIG. 3A. When such a dual layer disc isviewed upon as a single linear address range, this would lookschematically like shown in FIG. 3B.

Hence, a Hierarchical Fragment is embedded within a Session. Thisenables a user to leave a track within a Session open. This is possibledue to the fact that a track contains its own administration area. Now,it is possible for a disc drive to read what has been written and whathas not been written. Preferably, a DVD-ROM drive performs aHierarchical Fragment search when a disc is inserted to find the numberof such Fragments and to determine whether or not they are completelywritten.

FIG. 4 shows an example an embodiment comprising a hierarchy of threeHierarchical Fragments. Because a disc is filled linearly from the innerradius (on the left) to the outer radius (on the right), it remainsDVD-ROM compliant. The logical addresses run linearly over the entiredisc. Hence, within a closed Session or a closed Hierarchical Fragmentthere may be address zones that have not been written yet. However, aDVD-ROM drive will not have any problems with these unwritten addressesbecause a drive will jump between the layers immediately and not go tothe end of one layer before jumping to the next layer.

A device according to the present invention is capable of executing theabove-described methods according to the invention. Preferably, next tothe supported commands for reserving tracks, inquiring about theirsizes, and closing sessions, support for commands like 1) ReserveHierarchical Track, 2) Get Hierarchical Track Information, and 3) CloseHierarchical Track are implemented.

It is noted that although the invention is explained with reference to adual layer record carrier, the invention can also be used for recordcarriers comprising more than two information layers without deviatingfrom the concept of the invention

1. Method of recording information on a recordable multi-layer recordcarrier, said record carrier comprising a first information layer and asecond information layer for storing the information, whereininformation is incrementally recorded on the disc such that the arearegarded as containing written information on the first informationlayer is substantially equal to the area regarded as containing writteninformation on the second information layer.
 2. Method according toclaim 1, wherein the area regarded as containing written information onthe first information layer and/or the area regarded as containingwritten information on the second information layer comprise an areawhere no information is recorded.
 3. Recording device for recordinginformation on a recordable multi-layer record carrier operative forexecuting a method as claimed in claim 1.